clay street bridge replacement
HYDROLOGY /HYDRAULICS REPORT . EL DORADO COUNTY
CLAY STREET BRIDGE REPLACEMENT Prepared by:
Joseph Domenichelli Domenichelli & Associates 1107 Investment Blvd., Suite 145 El Dorado Hills, California 95762 (916) 933-1997 JULY 14, 2009
HYDROLOGY/HYDRAULICS REPORT Clay Street Bridge Replacement El Dorado County, California P R O J E C T L O C AT I O N A N D D E S C R I P T I O N Clay Street Bridge is located in El Dorado County near downtown Placerville. The existing bridge is a two-span concrete arch structure. Hangtown Creek flows under the north span of the bridge and the south span of the bridge serves as the outfall location for Cedar Ravine. Flow from Cedar Ravine joins Hangtown Creek directly downstream from the bridge. The existing bridge has a total span of approximately 60'-0" with a maximum opening width of approximately 21'-0" over the Hangtown Creek channel. The bridge width is approximately 19'-0". It is supported on concrete wall abutments at the banks and there is a central pier that ties into the concrete channel wall on the upstream side of the bridge. The central pier also separates Hangtown Creek and Cedar Ravine flow. The bridge width is insufficient for traffic demands and does not meet freeboard requirements for the 50-yr or 100-yr flows. There are existing utilities that run below or adjacent to the bridge. These utilities include sewer lines and manhole risers and a water line that is attached to the bridge on the west side. There are also multiple drain/culvert pipes and many unidentified pipes in the vicinity of the bridge. The in-channel utilities will be removed prior to bridge removal.
Figure 1 –Clay Street Bridge.
Figure 2 –Existing utilities downstream of Clay Street Bridge.
It is proposed to remove the existing bridge (including 8'x20' of concrete sill in channel) and replace it with a single span bridge that has a total open span length of 32'-0" and an overall width of 45'-6". The proposed bridge will have concrete barrier type 80SW (mod) with architectural treatment and barrier mounted iron railings. The bridge deck type has not been selected. It will either be a cast-in-place reinforced concrete slab with a depth of 2'-0" or a pre-cast pre-stressed slab with a depth of 1'-9". The City would like to minimize
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Clay Street Hydrology/Hydraulics
removal of the existing 66" corrugated metal culvert for Cedar Ravine. However, the proposed bridge design will require the Cedar Ravine pipe outlet to be reconstructed and the embankment regraded.
H A N G T O W N C R E E K A N D C E D A R R AV I N E H Y D R O L O G Y A hydrologic analysis was completed to establish design flows for the 50-yr and 100-yr events for Hangtown Creek and Cedar Ravine. A computer model was developed to determine these flows using the Army Corps of Engineers' Hydrologic Engineering Center's Hydrologic Modeling System (HEC-HMS version 3.0.1). The El Dorado County Drainage Manual was used in conjunction with the U.S. Department of Natural Resources Conservation Service (NRCS) to determine watershed conditions such as rainfall and soil data. Other watershed conditions such as channel storage potential, channel Manning's n-values and existing surface development were determined during a site visit. The City will require that flows from new developments within the watershed be mitigated to existing flow conditions so that peak flows in Hangtown Creek will not increase in the future. A flow verses frequency relationship for Hangtown Creek and Cedar Ravine are shown in the tables below. The combined flow for Hangtown Creek upstream of Clay Street and Cedar Ravine at Clay Street does not equal the flow at the confluence because the two stream hydrographs do not peak at the same time. Table 1: Peak flow rates for the 50-yr event. Location
Peak Flow Rate (cfs)
Hangtown Creek just upstream of Clay Street
2453
Cedar Ravine at Clay Street
381
Confluence of Hangtown Creek and Cedar Ravine
2782
Table 2: Peak flow rates for the 100-yr event. Location
Peak Flow Rate (cfs)
Hangtown Creek just upstream of Clay Street
2852
Cedar Ravine at Clay Street Confluence of Hangtown Creek and Cedar Ravine
450 3219
HANGTOWN CREEK HYDRAULICS Existing Conditions Model An existing conditions computer model was created for both Hangtown Creek and Cedar Ravine using the Army Corps of Engineers' Hydrologic Engineering Center River Analysis System (HEC-RAS version 3.1.3). Survey by Area West Engineers provided existing channel cross sections of Hangtown Creek both upstream and downstream of Clay Street. Manning's n-values for Hangtown Creek varied from 0.03 in the channel to 0.05 along the banks. A Manning's n-value of 0.014 was used for the concrete sill located in the channel on the downstream side of Clay Street Bridge.
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Clay Street Hydrology/Hydraulics
Figure 3 –Manning's n-values from 0.03-0.05 for HC.
Contraction and expansion coefficients of 0.3 and 0.5, respectively, were set in the vicinity of Clay Street Bridge and the Bedford Avenue Bridge downstream from Clay Street. The existing bridge geometry was entered into the model based on field measurements. Figure 4 and 5 show HEC-RAS cross-sections upstream and downstream of Clay Street Bridge. Figure 6 shows a profile through the existing bridge. The gray shaded areas represent blockage from structures such as the bridge deck/abutments. The top of existing bridge deck (not including railings) is at an elevation 1867.25 feet and the top soffit of the bridge arch is at an elevation of 1864.75 feet. Figure 4 –Existing conditions cross section (upstream). Clay Street
Plan: Existing Clay Street
River = Hangtown Creek Reach = Clay Street .03
Figure 5 –Existing conditions cross section (downstream).
.03
RS = 941.5 .045
BR
Clay Street Clay Street Bridge
.05
Plan: Existing Clay Street
River = Hangtown Creek Reach = Clay Street
.03
.03
1868
1868
Legend WS 100 YR WS 50 YR
1866
. 0 1 4
.03
. 0 1 4
RS = 941.5
BR
Clay Street Bridge
.045 Legend WS 100 YR WS 50 YR
1866
Ground
Ground
Ineff
Ineff
Bank Sta
1864
1862 Elevation (ft)
1862 Elevation (ft)
Bank Sta
1864
1860
1860
1858
1858
1856
1856
1854
1854
1852
1852 0
50
100
150
200
0
Station (ft)
50
100
150
200
Station (ft)
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Clay Street Hydrology/Hydraulics
Clay Street
Plan: Existing Clay Street Legend WS 100 YR WS 50 YR
1870
Ground LOB ROB
Elevation (ft)
1860
0
200
400
600
800
1000
Deck
1175
1079
931 Clay St Bridge
500
1840
861
645 Bedford Ave Bridge
1850
1200
Main Channel Distance (ft)
Figure 6 –Existing conditions 50-yr and 100-yr profile.
Approximately 249' upstream from Clay Street Bridge is a deck off of a building that spans over the channel. The deck is approximately 22' x 50' and it contains one pier that is one foot wide. Approximately 282' downstream of Clay Street Bridge is Bedford Avenue Bridge. This bridge is 19' wide with a 26' span. The existing model was run with the flows described previously. Results in the vicinity of Clay Street Bridge are presented in the following tables. Table 3: 50-yr water surface elevations and velocities for the existing bridge. Cross-section (River Sta)
Location Relative to Bridge
WSEL (feet)
Channel Velocity (fps)
294' upstream
1870.0
7.2
1175
234' upstream
1866.4
13.9
1079
138' upstream
1865.5
10.6
953
12' upstream
1865.2
10.0
931
11' downstream
1862.7
16.2
861
81' downstream
1863.9
7.2
1235 Deck off of house
Clay Street Bridge
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Clay Street Hydrology/Hydraulics
Cross-section (River Sta)
Location Relative to Bridge
WSEL (feet)
Channel Velocity (fps)
268' downstream
1863.6
6.4
645
297' downstream
1860.6
13.1
500
442' downstream
1859.9
10.6
0
942' downstream
1849.9
10.6
674 Bedford Ave Bridge
Table 4: 100-yr water surface elevations and velocities for the existing bridge. Cross-section (River Sta)
Location Relative to Bridge
WSEL (feet)
Channel Velocity (fps)
294' upstream
1870.6
6.8
1175
234' upstream
1867.3
13.9
1079
138' upstream
1867.7
8.2
953
12' upstream
1866.7
10.3
931
11' downstream
1863.5
17.0
861
81' downstream
1864.3
7.7
674
268' downstream
1864.0
6.8
645
297' downstream
1862.1
10.9
500
442' downstream
1860.3
10.8
0
942' downstream
1850.3
10.8
1235 Deck off of house
Clay Street Bridge
Bedford Ave Bridge
As seen in the profile and related tables the existing bridge will nearly overtop during the 100-yr flood event and will pass the 50-yr flow with no clearance to the soffit.
Proposed Conditions Model The existing conditions model was modified to create the proposed conditions model. The proposed conditions model contains the new bridge geometry provided by Quincy Engineering, Inc. The proposed geometry was inserted into the model based on the provided plans shown in Appendix A. The alternative with the 2'-0" thick cast-in-place reinforced concrete slab was modeled for this analysis as hydraulically the most conservative alternative. If the alternative with the thicker slab meets clearance requirements then the other alternative will also meet clearance requirements. The proposed single span bridge will exceed the total width of the existing bridge by approximately 26'-6". Since the proposed bridge is much wider than the existing bridge, additional cross sections upstream and downstream from the bridge were created based on the topography provided by Quincy Engineering. The right side of the bridge was brought in 2 feet to account for debris that could potentially gather around the right side of the bridge abutment. Figure 7 and 8 show HEC-RAS cross-sections upstream and downstream of Clay Street Bridge. Figure 9 shows a profile through the new bridge. The top of the new bridge deck (not including the concrete barrier and hand railing) is at an elevation of 1868.57 feet and the bottom soffit of the bridge is at an elevation of 1866.57 feet.
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Clay Street Hydrology/Hydraulics
Clay Street Plan: Final_Proposed Clay Street RS = 967.25 BR Clay Street Bridge .045
Clay Street Plan: Final_Proposed Clay Street RS = 967.25 BR Clay Street Bridge
.03
.045
1870
.03
1870
Legend
Legend
WS 100 YR
WS 100 YR
1868
1868 WS 50 YR
WS 50 YR
Ground
1866
Ground
1866
Ineff
1862
1862
1860
1860
1858
1858
1856
1856
1854 -40
-20
0
20
40
60
Bank Sta
1864 Elevation (ft)
Elevation (ft)
Ineff
Bank Sta
1864
1854 -40
80
-20
0
20
Station (ft)
40
60
80
Station (ft)
Figure 7 – Proposed conditions cross section (upstream).
Clay Street
Figure 8 – Proposed conditions cross section (downstream).
Plan: Final_Proposed Clay Street
Hangtow n Creek Clay Street 1875
Legend WS 100 YR
1870
WS 50 YR Ground LOB
1865
ROB
Elevation (ft)
1860
1855
Deck
1175
1079
1034.75
Clay St Bridge
500
1840
861
645 Bedford Ave Bridge
1845
921.25
1850
1835 0
200
400
600
800
1000
1200
1400
Main Channel Distance (ft)
Figure 9 – Proposed conditions 50-yr and 100-yr profile.
The same flow rates as in the existing conditions model were run with the new bridge in place. Results in the vicinity of the new bridge are presented in the following tables. Table 5: 50-yr water surface elevations and velocities for the proposed bridge. Cross-section (River Sta) 1235
WSEL (feet)
Channel Velocity (fps)
245' upstream
1870.0
6.7
185' upstream
1866.4
13.8
Location Relative to Bridge
Deck off of house 1175
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Clay Street Hydrology/Hydraulics
Cross-section (River Sta)
Location Relative to Bridge
WSEL (feet)
Channel Velocity (fps) 9.2
1079
89' upstream
1866.3
1034.75
45' upstream
1866.4
7.6
995.25
5' upstream
1864.9
11.1
939.25
5' downstream
1863.1
14.2
921.25
23’ downstream
1863.4
10.3
861
84' downstream
1863.9
7.2
674
271' downstream
1863.6
6.4
645
300' downstream
1860.6
13.1
500
445' downstream
1859.9
10.6
0
945' downstream
1849.9
10.6
Clay Street Bridge
Bedford Ave Bridge
Table 6: 100-yr water surface elevations and velocities for the proposed bridge. WSEL (feet)
Channel Velocity (fps)
245' upstream
1870.6
6.9
1175
185' upstream
1867.3
13.9
1079
89' upstream
1867.3
9.0
1034.75
45' upstream
1867.3
7.8
995.25
5' upstream
1865.6
11.8
939.25
5' downstream
1863.9
14.6
921.25
23’ downstream
1863.5
11.7
861
84' downstream
1864.3
7.7
674
271' downstream
1864.0
6.8
645
300' downstream
1862.1
10.9
500
445' downstream
1860.3
10.8
0
945' downstream
1850.3
10.8
Cross-section (River Sta) 1235
Location Relative to Bridge
Deck off of house
Clay Street Bridge
Bedford Ave Bridge
Based on the results, the proposed bridge deck will have 1.73 feet of clearance between the deck soffit and the 50-yr water surface and can pass the 100-yr flow with 1.0 foot of clearance (shown in Table 7), therefore, exceeding clearance and freeboard requirements. It is important to note that freeboard was calculated from top of deck and clearance was calculated from soffit. Table 7: Top of deck freeboard and soffit clearance for 50-yr and 100-yr events. 100-yr Freeboard (ft)
50-yr Freeboard (ft)
100-yr Soffit Clearance (ft)
50-yr Soffit Clearance (ft)
Existing Conditions
0.5
2.0
0.0
0.0
Proposed Condition
3.0
3.73
1.0
1.73
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Clay Street Hydrology/Hydraulics
Table 8 provides a comparison between existing conditions and the proposed bridge conditions water surfaces immediately upstream of the bridges and at cross section 861 downstream of the bridges. The models show no difference in water surface elevations downstream from the bridge. The models show that the upstream water surface elevations decrease with the new bridge. The models also show the velocities slowing down through the new bridge. Therefore, the new bridge will have no negative impacts to the Hangtown Creek floodplain. Table 8: Comparison of water surface elevations and velocities for 50-yr and 100-yr events. 100-year Event
50-yr Event
WSE Downstream of Bridge (ft)
WSE Upstream of Bridge (ft)
Velocity through Bridge (fps)
WSE Downstream of Bridge (ft)
WSE Upstream of Bridge (ft)
Velocity through Bridge (fps)
Existing Conditions
1864.3
1866.8
16.6
1863.9
1865.3
15.2
Proposed Condition
1864.3
1865.6
11.9
1863.9
1864.9
11.3
Difference
0.0
-1.2
-4.7
0.0
-0.4
-3.9
C E D A R R AV I N E H Y D R A U L I C S Existing Conditions Model An existing conditions computer model was created for Cedar Ravine using the Army Corps of Engineers' Hydrologic Engineering Center River Analysis System (HEC-RAS version 3.1.3). Survey by Area West Engineers provided cross sections upstream on Cedar Ravine. The modeled portion of Cedar Ravine consists of approximately 40 feet of open channel that flows into a 4' x 7.8' box culvert. The box culvert extends for about 234 feet and then it transitions into a 66" corrugated metal pipe that extends for approximately 286 feet where it outlets into Hangtown Creek. Due to limited survey, all lengths and dimensions were approximated during a site visit. A Manning's n-value of 0.025 was used for the open channel segment of Cedar Ravine. Manning's nvalues of 0.017 and 0.024 were used for the box culvert segment and corrugated metal pipe segment, respectively. Cross sections and Manning's n-values downstream from the confluence of Hangtown Creek and Cedar Ravine remained the same as in the existing conditions model for Hangtown Creek.
Figure 10 –Manning's n-value of 0.025 for Cedar Ravine.
8
Figure 11 –Manning's n-value of 0.017 for box culvert.
Clay Street Hydrology/Hydraulics
The results show that Cedar Ravine cannot convey the 50-yr and 100-yr event flows through the culverts and some roadway flooding is anticipated during major storm events. Table 9 shows results for the culvert. Table 9: Flow vs. capacity for Cedar Ravine culvert. Location
Flow Rate (cfs)
Approximate flow conveyed in culvert
300
50-yr event flow
381
100-yr event flow
450
S C O U R A N A LY S I S A scour analysis of the Clay Street Bridge at Hangtown Creek was performed for the proposed bridge replacement (cast-in-place 2'-0" reinforced concrete slab). The other alternative was not analyzed because there should not be any significant difference in scour due to similar bridge alignment and dimensions. Evaluation of scour at the bridge is based on criteria and methodologies developed by the Federal Highways Administration, Hydraulic Circular No. 18 (HEC-18), Evaluating Scour at Bridges (February 1993). The analysis estimates scour potential that is based primarily on channel hydraulics, without consideration for streambed surface and subsurface conditions. It should be noted that the predictive scour equations were developed from laboratory tests using fine granular materials. The resulting values of estimated potential scour are typically conservative, especially in cases where the depth to scour resistant materials is shallower than the estimated scour depth.
H y d r a u l i c Va r i a b l e s Hydraulics variables such as channel flow, velocity and depth are adapted from the HEC-RAS Hydraulic Model for Hangtown Creek at the proposed Clay Street Bridge.
Soils Investigation A preliminary foundation report was created by Taber. The report states that the stream channel contains bedrock that shows little erosion from flow and it appears to be scour resistant. Although the extent and depth of bedrock in the channel was not stated, the depth of scour resistant materials can be expected to be less than the calculated scour depths. When designing bridge foundations, depth to this scour resistant material should be accurately determined.
L o n g Te r m A g g r a d a t i o n a n d D e g r a d a t i o n Long term changes in streambeds may be either by aggradation (filling) or degradation (cutting) of the streambed over long periods of time. Long term changes differ from short term modifications in that changes are not apparent within the year, as is the case with local scour of the streambed at bridges. Generally, short term (local) changes result from bridge hydraulics, while long-term changes are associated with changes in the hydraulics of the stream itself. Thus, long-term changes are noticeable throughout the stream reach and not just at bridge locations.
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Clay Street Hydrology/Hydraulics
Due to the presence of exposed bedrock along the channel bottom of Hangtown Creek, there are no significant signs of long-term aggradation or degradation. However, a value of 1 foot degradation has been assumed for conservative analysis.
Contraction and Pier Scour There is no contraction scour due to the alignment of the new bridge and there is no pier scour because the new single span bridge does not have piers.
Local Abutment Scour Local abutment scour occurs when the abutment obstructs the flow. In the case of the Clay Street Bridge the right and left abutment scour is fairly similar. The abutment scour was calculated using Froehlich’s equation as described in HEC-18. The abutment scour was calculated for the worst case conditions using the channel capacity flow conditions. ⎛ a' Ys = 2.27 × K 1 × K 2 × ⎜⎜ Ya ⎝ Ya
⎞ ⎟⎟ ⎠
0.43
× Fr 0.61 + 1
where : K 1 = vertical wall K 2 = angle coeff. a' = Projection into Normal flow Ya = average depth of flow on the floodplain Fr = Froude number of approach upstream of the abutment Fr =
Ve (g × y a )1/2
Ve = Average velocity in overbank g = 32.2 ft/sec
Table 10 below shows the variables for the right and left abutment scour calculations and the total scour calculated. Table 10. Variables for abutment scour calculations. Right Abutment
Left Abutment
K1
1.0
1.0
K2
1.0
1.0
a’ (ft)
15.9
56.4
Fr
0.37
0.41
ya (ft)
1.85
0.85
ys (ft)
7.6
7.7
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Clay Street Hydrology/Hydraulics
To t a l S c o u r P o t e n t i a l a n d R e c o m m e n d a t i o n s The scour potential at the Clay Street Bridge at Hangtown Creek consists mostly of abutment scour. The maximum scour expected at the abutments is 7.6 feet for the right abutment and 7.7 feet for the left abutment. However, it is important to note that bedrock exists in this area and that abutment scour will only occur to the depth of bedrock. Rock protection is recommended at the abutments if foundation exposure is an issue. If rock protection is necessary, it should consist of standard Caltrans facing material with a minimum thickness of 1.8 feet for a width of 5 feet along each abutment. Significant scour is not anticipated at the confluence of Hangtown Creek and Cedar Ravine due to the proposed alignment of the new bridge and the outlet of Cedar Ravine. The proposed alignment of Cedar Ravine outlet will direct flow inline (parallel) with the flow of Hangtown Creek reducing cross bank flow and turbulence from that of the existing alignment. The existing rock channel bottom has not experienced significant sour downstream of the confluence, therefore the improved condition is not expected to show any measurable scour. If existing rock downstream from the culvert outlet is removed during construction it should be replaced in-kind or using Caltrans facing material as described above. The limits of the rock protection should extend approximately 20 feet downstream from the culvert outlet.
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Clay Street Hydrology/Hydraulics
APPENDIX A - PROPOSED BRIDGE PLANS
Clay Street Bridge H & H Analysis
APPENDIX B - HEC-HMS OUTPUT
Clay Street Bridge H & H Analysis
HEC-HMS SCHEMATIC FOR THE 50-YR AND 100-YR EVENTS
AREA OF INTEREST
Project: Clay Street Brdg
Simulation Run: Existing 50YR
Start of Run: 01Jan2006, 00:00 End of Run: 02Jan2006, 00:00 Compute Time: 15Nov2007, 08:45:30 Volume Units:
Basin Model: Existing Meteorologic Model: GAGE 50YR Control Specifications: 1-day
AC-FT
Hydrologic Element
Drainage Area (MI2)
Peak Discharge Time of Peak (CFS)
Volume (AC-FT)
A1
0.5950
363.55
01Jan2006, 12:32
116.64
C1
0.4761
267.69
01Jan2006, 12:32
92.32
C2
0.0555
44.48
01Jan2006, 12:16
12.53
C3
0.3050
238.37
01Jan2006, 12:17
61.51
CR
0.8366
381.27
01Jan2006, 12:20
165.60
HC_CR
5.5396
2782.33
01Jan2006, 12:33
1023.52
HT1
0.2400
138.65
01Jan2006, 12:30
43.21
HT2
0.3160
208.84
01Jan2006, 12:21
57.82
HT3
0.1680
154.25
01Jan2006, 12:19
41.95
HT4
0.1010
104.94
01Jan2006, 12:18
29.34
HT5
0.0650
47.77
01Jan2006, 12:17
12.32
HT6
0.0750
63.96
01Jan2006, 12:16
16.59
HT7
0.0720
63.94
01Jan2006, 12:22
18.36
J1
1.3180
597.39
01Jan2006, 12:41
205.10
J2
4.6310
2396.34
01Jan2006, 12:32
841.32
J3
0.7660
522.51
01Jan2006, 12:24
155.57
J4
1.6010
1021.15
01Jan2006, 12:29
314.74
J5
1.9170
1205.27
01Jan2006, 12:28
372.31
J6
2.4650
1456.65
01Jan2006, 12:29
472.60
J7
2.8080
1595.69
01Jan2006, 12:30
527.30
J9
0.3100
108.74
01Jan2006, 12:31
45.37
L1
0.0500
21.69
01Jan2006, 12:25
6.36
L1.2
0.0960
50.38
01Jan2006, 12:15
12.75
L1.3
0.1360
65.88
01Jan2006, 12:28
20.01
L2
0.0700
60.10
01Jan2006, 12:10
13.73
Page 1
Hydrologic Element
Drainage Area (MI2)
Peak Discharge Time of Peak (CFS)
Volume (AC-FT)
L2.2
0.0280
34.11
01Jan2006, 12:04
6.67
R1
0.5340
239.58
01Jan2006, 12:38
81.67
R1-R2
0.5340
239.48
01Jan2006, 12:46
80.93
R2
0.7840
370.43
01Jan2006, 12:36
124.17
R2-R3
1.3180
597.16
01Jan2006, 12:46
203.84
R3
0.4300
331.91
01Jan2006, 12:22
94.13
RC1
0.5316
236.37
01Jan2006, 12:56
104.09
RES-C1
0.5316
236.44
01Jan2006, 12:48
104.81
RES-LL
0.1860
76.92
01Jan2006, 12:37
25.98
RHT-1
0.7660
522.20
01Jan2006, 12:28
154.89
RHT-10
0.1860
76.92
01Jan2006, 12:38
25.95
RHT-11
0.3100
108.73
01Jan2006, 12:32
45.35
RHT-12
0.3100
108.72
01Jan2006, 12:33
45.28
RHT-2
1.6010
1020.83
01Jan2006, 12:30
314.49
RHT-6
1.9170
1204.82
01Jan2006, 12:30
371.63
RHT-7
2.4650
1452.78
01Jan2006, 12:31
471.28
RHT-8
2.8080
1594.41
01Jan2006, 12:31
526.76
RHT-9
4.6310
2389.18
01Jan2006, 12:34
839.56
S1
0.1770
53.84
01Jan2006, 12:15
14.35
SM1
0.5850
380.84
01Jan2006, 12:26
113.84
SM2
0.1810
154.46
01Jan2006, 12:19
41.74
Page 2
Project: Clay Street Brdg
Simulation Run: Gage 100YR
Start of Run: 01Jan2006, 00:00 End of Run: 02Jan2006, 00:00 Compute Time: 15Nov2007, 08:43:49 Volume Units:
Basin Model: Existing Meteorologic Model: Gage 100YR Control Specifications: 1-day
AC-FT
Hydrologic Element
Drainage Area (MI2)
Peak Discharge Time of Peak (CFS)
Volume (AC-FT)
A1
0.5950
418.01
01Jan2006, 12:31
133.73
C1
0.4761
308.36
01Jan2006, 12:32
105.87
C2
0.0555
50.90
01Jan2006, 12:16
14.27
C3
0.3050
276.06
01Jan2006, 12:16
71.79
CR
0.8366
450.13
01Jan2006, 12:42
191.07
HC_CR
5.5396
3219.30
01Jan2006, 12:33
1183.79
HT1
0.2400
160.91
01Jan2006, 12:29
49.95
HT2
0.3160
243.03
01Jan2006, 12:21
66.97
HT3
0.1680
174.17
01Jan2006, 12:18
47.52
HT4
0.1010
116.79
01Jan2006, 12:18
32.72
HT5
0.0650
55.56
01Jan2006, 12:17
14.39
HT6
0.0750
73.34
01Jan2006, 12:16
19.09
HT7
0.0720
71.83
01Jan2006, 12:22
20.90
J1
1.3180
703.50
01Jan2006, 12:40
240.59
J2
4.6310
2789.80
01Jan2006, 12:32
973.90
J3
0.7660
602.14
01Jan2006, 12:24
179.02
J4
1.6010
1176.67
01Jan2006, 12:29
361.91
J5
1.9170
1391.98
01Jan2006, 12:28
428.59
J6
2.4650
1686.46
01Jan2006, 12:28
545.03
J7
2.8080
1849.82
01Jan2006, 12:30
609.04
J9
0.3100
130.86
01Jan2006, 12:30
53.81
L1
0.0500
26.22
01Jan2006, 12:25
7.61
L1.2
0.0960
61.18
01Jan2006, 12:15
15.32
L1.3
0.1360
78.19
01Jan2006, 12:28
23.57
L2
0.0700
70.39
01Jan2006, 12:10
15.99
Page 1
Hydrologic Element
Drainage Area (MI2)
Peak Discharge Time of Peak (CFS)
Volume (AC-FT)
L2.2
0.0280
40.03
01Jan2006, 12:04
7.80
R1
0.5340
282.26
01Jan2006, 12:37
95.59
R1-R2
0.5340
282.14
01Jan2006, 12:46
94.74
R2
0.7840
434.69
01Jan2006, 12:36
145.85
R2-R3
1.3180
703.16
01Jan2006, 12:46
239.11
R3
0.4300
379.04
01Jan2006, 12:22
107.29
RC1
0.5316
330.37
01Jan2006, 12:43
119.28
RES-C1
0.5316
335.41
01Jan2006, 12:35
120.09
RES-LL
0.1860
92.06
01Jan2006, 12:37
30.71
RHT-1
0.7660
601.78
01Jan2006, 12:28
178.24
RHT-10
0.1860
92.04
01Jan2006, 12:38
30.68
RHT-11
0.3100
130.82
01Jan2006, 12:30
53.79
RHT-12
0.3100
130.81
01Jan2006, 12:32
53.71
RHT-2
1.6010
1176.32
01Jan2006, 12:30
361.62
RHT-6
1.9170
1391.44
01Jan2006, 12:30
427.81
RHT-7
2.4650
1682.13
01Jan2006, 12:31
543.49
RHT-8
2.8080
1848.20
01Jan2006, 12:31
608.41
RHT-9
4.6310
2780.51
01Jan2006, 12:34
971.82
S1
0.1770
70.99
01Jan2006, 12:15
18.43
SM1
0.5850
440.21
01Jan2006, 12:26
131.44
SM2
0.1810
176.62
01Jan2006, 12:19
47.57
Page 2
APPENDIX C - HEC-RAS OUTPUT FOR HANGTOWN CREEK
Clay Street Bridge H & H Analysis
HEC-RAS Plan: Existing River: Hangtown Creek Reach: Clay Street Reach
River Sta
Profile
Q Total
Min Ch El
W.S. Elev
Crit W.S.
E.G. Elev
E.G. Slope
Vel Chnl
Flow Area
Top Width
(cfs)
(ft)
(ft)
(ft)
(ft)
(ft/ft)
(ft/s)
(sq ft)
(ft)
Froude # Chl
Clay Street
1235
100 YR
2852.00
1857.75
1870.61
1867.31
1871.22
0.002226
6.79
474.51
88.24
0.38
Clay Street
1235
50 YR
2453.00
1857.75
1870.02
1866.39
1870.61
0.002279
6.64
422.51
88.24
0.38
Clay Street
1190
Clay Street
1175
100 YR
2852.00
1857.75
1867.31
1867.31
1870.28
0.014654
13.89
208.62
38.96
0.94
Clay Street
1175
50 YR
2453.00
1857.75
1866.39
1866.39
1869.38
0.017418
13.89
176.61
30.69
1.01
Clay Street
1079
100 YR
2852.00
1856.40
1867.71
1868.75
0.005667
8.24
361.13
99.30
0.57
Clay Street
1079
50 YR
2453.00
1856.40
1865.53
1867.27
0.013011
10.57
232.09
45.18
0.82
Clay Street
953
100 YR
2852.00
1852.69
1866.70
1861.84
1868.36
0.001495
10.33
276.19
183.84
0.50
Clay Street
953
50 YR
2453.00
1852.69
1865.20
1861.03
1866.76
0.001656
10.03
244.66
32.05
0.52
Clay Street
941.5
Clay Street
931
100 YR
3219.00
1853.20
1863.49
1863.49
1867.99
0.004535
17.03
189.05
46.71
1.00
Clay Street
931
50 YR
2782.00
1853.20
1862.65
1862.65
1866.74
0.004686
16.22
171.52
44.32
1.00
Clay Street
861
100 YR
3219.00
1852.08
1864.26
1865.07
0.002850
7.66
479.25
112.40
0.46
Clay Street
861
50 YR
2782.00
1852.08
1863.89
1864.61
0.002649
7.17
438.25
107.15
0.44
Clay Street
674
100 YR
3219.00
1850.42
1863.98
1862.14
1864.56
0.002002
6.81
558.35
108.91
0.36
Clay Street
674
50 YR
2782.00
1850.42
1863.63
1859.44
1864.14
0.001829
6.38
520.12
108.91
0.34
Clay Street
659.5
Clay Street
645
100 YR
3219.00
1850.42
1862.14
1862.14
1863.74
0.005943
10.85
357.76
108.91
0.62
Clay Street
645
50 YR
2782.00
1850.42
1860.64
1859.44
1863.30
0.010464
13.10
214.22
81.01
0.81
Clay Street
500
100 YR
3219.00
1847.91
1860.32
1860.32
1861.87
0.007719
10.75
358.30
108.90
0.65
Clay Street
500
50 YR
2782.00
1847.91
1859.86
1859.86
1861.42
0.008063
10.59
308.77
103.30
0.66
Clay Street
0
100 YR
3219.00
1837.91
1850.32
1850.32
1851.87
0.007719
10.75
358.30
108.90
0.65
Clay Street
0
50 YR
2782.00
1837.91
1849.86
1849.86
1851.42
0.008063
10.59
308.77
103.30
0.66
Bridge
Bridge
Bridge
1
HEC-RAS Plan: Final_Proposed River: Hangtown Creek Reach: Clay Street Reach
River Sta
Profile
Q Total (cfs) 2852.00
Min Ch El (ft) 1857.75
W.S. Elev (ft) 1870.60
Crit W.S. (ft) 1867.29
E.G. Elev (ft) 1871.22
E.G. Slope (ft/ft) 0.002148
Vel Chnl (ft/s) 6.86
Flow Area (sq ft) 473.51
Top Width (ft) 88.24
Froude # Chl
2453.00
1857.75
1870.01
1866.39
1870.60
0.002192
6.70
421.50
88.24
0.38
1867.29 1866.41
1870.29 1869.38
0.013875 0.016189
13.92 13.84
208.12 177.23
38.85 30.87
0.94 1.00
Clay Street
1235
100 YR
Clay Street
1235
50 YR
0.38
Clay Street
1190
Clay Street Clay Street
1175 1175
100 YR 50 YR
2852.00 2453.00
1857.75 1857.75
1867.29 1866.41
Clay Street
1079
100 YR
2852.00
1856.40
1867.28
1868.53
0.007300
8.97
320.71
79.31
0.64
Clay Street
1079
50 YR
2453.00
1856.40
1866.29
1867.59
0.008831
9.18
267.32
48.57
0.69
Clay Street Clay Street
1034.75 1034.75
100 YR 50 YR
2852.00 2453.00
1856.00 1856.00
1867.31 1866.36
1863.82 1863.24
1868.25 1867.25
0.002764 0.003062
7.78 7.55
366.62 324.79
112.58 90.13
0.48 0.49
Clay Street
995.25
100 YR
2852.00
1855.00
1865.61
1864.04
1867.76
0.003911
11.75
242.69
87.77
0.73
Clay Street
995.25
50 YR
2453.00
1855.00
1864.89
1863.33
1866.80
0.003954
11.10
220.98
57.06
0.72
Clay Street
967.25
Clay Street Clay Street
939.25 939.25
100 YR 50 YR
2852.00 2453.00
1854.50 1854.50
1863.85 1863.10
1863.85 1863.10
1867.17 1866.21
0.008068 0.008266
14.63 14.15
194.90 173.37
50.22 47.75
1.00 1.01
Clay Street Clay Street
921.25 921.25
100 YR 50 YR
3219.00 2782.00
1854.00 1854.00
1863.53 1863.41
1865.67 1865.06
0.003878 0.003046
11.73 10.29
274.49 270.36
46.64 46.27
0.74 0.65
Clay Street Clay Street
861 861
100 YR 50 YR
3219.00 2782.00
1852.08 1852.08
1864.26 1863.89
1865.07 1864.61
0.002850 0.002649
7.66 7.17
479.25 438.25
112.40 107.15
0.46 0.44
Clay Street Clay Street
674 674
100 YR 50 YR
3219.00 2782.00
1850.42 1850.42
1863.98 1863.63
1862.14 1859.44
1864.56 1864.14
0.002002 0.001829
6.81 6.38
558.35 520.12
108.91 108.91
0.36 0.34
Clay Street
659.5
Clay Street Clay Street
645 645
100 YR 50 YR
3219.00 2782.00
1850.42 1850.42
1862.14 1860.64
1862.14 1859.44
1863.74 1863.30
0.005943 0.010464
10.85 13.10
357.76 214.22
108.91 81.01
0.62 0.81
Clay Street Clay Street
500 500
100 YR 50 YR
3219.00 2782.00
1847.91 1847.91
1860.32 1859.86
1860.32 1859.86
1861.87 1861.42
0.007719 0.008063
10.75 10.59
358.30 308.77
108.90 103.30
0.65 0.66
Clay Street Clay Street
0 0
100 YR 50 YR
3219.00 2782.00
1837.91 1837.91
1850.32 1849.86
1850.32 1849.86
1851.87 1851.42
0.007719 0.008063
10.75 10.59
358.30 308.77
108.90 103.30
0.65 0.66
Bridge
Bridge
Bridge
1
A P P E N D I X D - H E C - R A S O U T P U T F O R C E D A R R AV I N E
Clay Street Bridge H & H Analysis
HEC-RAS Plan: Existing River: Cedar Ravine Reach: Cedar Ravine Reach
River Sta
Profile
Q Total
Min Ch El
W.S. Elev
Crit W.S.
E.G. Elev
E.G. Slope
Vel Chnl
Flow Area
Top Width
Froude # Chl
(cfs) 450.00
(ft) 1870.16
(ft) 1878.05
(ft) 1875.34
(ft) 1878.28
(ft/ft) 0.001029
(ft/s) 4.40
(sq ft) 129.87
(ft) 50.18
0.29
381.00
1870.16
1876.38
1874.78
1877.16
0.004098
7.32
59.29
28.43
0.56
1876.94 1876.48
0.001673 0.002130
5.36 5.71
106.74 80.94
50.18 40.46
0.37 0.41
Cedar Ravine
1536
100YR
Cedar Ravine
1536
50YR
Cedar Ravine
1521
Cedar Ravine Cedar Ravine
1506 1506
100YR 50YR
450.00 381.00
1869.16 1869.16
1876.59 1876.04
Cedar Ravine
1466
100YR
450.00
1868.66
1876.65
1873.40
1876.85
0.000939
4.07
137.11
50.18
0.27
Cedar Ravine
1466
50YR
381.00
1868.66
1876.13
1872.86
1876.36
0.001157
4.30
110.82
50.18
0.29
Cedar Ravine
1345.25
Cedar Ravine Cedar Ravine
1224.5 1224.5
1864.17 1864.17
1874.11 1873.10
1870.09 1869.46
1874.94 1873.88
0.002390 0.002453
7.29 7.08
61.74 53.78
7.83 7.83
0.46 0.48
Cedar Ravine
1077.75
Cedar Ravine Cedar Ravine
931 931
100YR 50YR
450.00 381.00
1853.20 1853.20
1863.42 1863.27
1865.14 1864.55
0.002918 0.002237
10.51 9.08
42.84 41.98
46.53 46.08
0.66 0.58
Cedar Ravine Cedar Ravine
861 861
100YR 50YR
450.00 381.00
1852.08 1852.08
1864.26 1863.89
1864.28 1863.90
0.000056 0.000050
1.07 0.98
479.39 438.76
112.41 107.22
0.06 0.06
Bridge
Culvert 100YR 50YR
450.00 381.00 Culvert
1855.31 1855.05
1
CLAY STREET BRIDGE REPLACEMENT Prepared by:
Joseph Domenichelli Domenichelli & Associates 1107 Investment Blvd., Suite 145 El Dorado Hills, California 95762 (916) 933-1997 JULY 14, 2009
HYDROLOGY/HYDRAULICS REPORT Clay Street Bridge Replacement El Dorado County, California P R O J E C T L O C AT I O N A N D D E S C R I P T I O N Clay Street Bridge is located in El Dorado County near downtown Placerville. The existing bridge is a two-span concrete arch structure. Hangtown Creek flows under the north span of the bridge and the south span of the bridge serves as the outfall location for Cedar Ravine. Flow from Cedar Ravine joins Hangtown Creek directly downstream from the bridge. The existing bridge has a total span of approximately 60'-0" with a maximum opening width of approximately 21'-0" over the Hangtown Creek channel. The bridge width is approximately 19'-0". It is supported on concrete wall abutments at the banks and there is a central pier that ties into the concrete channel wall on the upstream side of the bridge. The central pier also separates Hangtown Creek and Cedar Ravine flow. The bridge width is insufficient for traffic demands and does not meet freeboard requirements for the 50-yr or 100-yr flows. There are existing utilities that run below or adjacent to the bridge. These utilities include sewer lines and manhole risers and a water line that is attached to the bridge on the west side. There are also multiple drain/culvert pipes and many unidentified pipes in the vicinity of the bridge. The in-channel utilities will be removed prior to bridge removal.
Figure 1 –Clay Street Bridge.
Figure 2 –Existing utilities downstream of Clay Street Bridge.
It is proposed to remove the existing bridge (including 8'x20' of concrete sill in channel) and replace it with a single span bridge that has a total open span length of 32'-0" and an overall width of 45'-6". The proposed bridge will have concrete barrier type 80SW (mod) with architectural treatment and barrier mounted iron railings. The bridge deck type has not been selected. It will either be a cast-in-place reinforced concrete slab with a depth of 2'-0" or a pre-cast pre-stressed slab with a depth of 1'-9". The City would like to minimize
1
Clay Street Hydrology/Hydraulics
removal of the existing 66" corrugated metal culvert for Cedar Ravine. However, the proposed bridge design will require the Cedar Ravine pipe outlet to be reconstructed and the embankment regraded.
H A N G T O W N C R E E K A N D C E D A R R AV I N E H Y D R O L O G Y A hydrologic analysis was completed to establish design flows for the 50-yr and 100-yr events for Hangtown Creek and Cedar Ravine. A computer model was developed to determine these flows using the Army Corps of Engineers' Hydrologic Engineering Center's Hydrologic Modeling System (HEC-HMS version 3.0.1). The El Dorado County Drainage Manual was used in conjunction with the U.S. Department of Natural Resources Conservation Service (NRCS) to determine watershed conditions such as rainfall and soil data. Other watershed conditions such as channel storage potential, channel Manning's n-values and existing surface development were determined during a site visit. The City will require that flows from new developments within the watershed be mitigated to existing flow conditions so that peak flows in Hangtown Creek will not increase in the future. A flow verses frequency relationship for Hangtown Creek and Cedar Ravine are shown in the tables below. The combined flow for Hangtown Creek upstream of Clay Street and Cedar Ravine at Clay Street does not equal the flow at the confluence because the two stream hydrographs do not peak at the same time. Table 1: Peak flow rates for the 50-yr event. Location
Peak Flow Rate (cfs)
Hangtown Creek just upstream of Clay Street
2453
Cedar Ravine at Clay Street
381
Confluence of Hangtown Creek and Cedar Ravine
2782
Table 2: Peak flow rates for the 100-yr event. Location
Peak Flow Rate (cfs)
Hangtown Creek just upstream of Clay Street
2852
Cedar Ravine at Clay Street Confluence of Hangtown Creek and Cedar Ravine
450 3219
HANGTOWN CREEK HYDRAULICS Existing Conditions Model An existing conditions computer model was created for both Hangtown Creek and Cedar Ravine using the Army Corps of Engineers' Hydrologic Engineering Center River Analysis System (HEC-RAS version 3.1.3). Survey by Area West Engineers provided existing channel cross sections of Hangtown Creek both upstream and downstream of Clay Street. Manning's n-values for Hangtown Creek varied from 0.03 in the channel to 0.05 along the banks. A Manning's n-value of 0.014 was used for the concrete sill located in the channel on the downstream side of Clay Street Bridge.
2
Clay Street Hydrology/Hydraulics
Figure 3 –Manning's n-values from 0.03-0.05 for HC.
Contraction and expansion coefficients of 0.3 and 0.5, respectively, were set in the vicinity of Clay Street Bridge and the Bedford Avenue Bridge downstream from Clay Street. The existing bridge geometry was entered into the model based on field measurements. Figure 4 and 5 show HEC-RAS cross-sections upstream and downstream of Clay Street Bridge. Figure 6 shows a profile through the existing bridge. The gray shaded areas represent blockage from structures such as the bridge deck/abutments. The top of existing bridge deck (not including railings) is at an elevation 1867.25 feet and the top soffit of the bridge arch is at an elevation of 1864.75 feet. Figure 4 –Existing conditions cross section (upstream). Clay Street
Plan: Existing Clay Street
River = Hangtown Creek Reach = Clay Street .03
Figure 5 –Existing conditions cross section (downstream).
.03
RS = 941.5 .045
BR
Clay Street Clay Street Bridge
.05
Plan: Existing Clay Street
River = Hangtown Creek Reach = Clay Street
.03
.03
1868
1868
Legend WS 100 YR WS 50 YR
1866
. 0 1 4
.03
. 0 1 4
RS = 941.5
BR
Clay Street Bridge
.045 Legend WS 100 YR WS 50 YR
1866
Ground
Ground
Ineff
Ineff
Bank Sta
1864
1862 Elevation (ft)
1862 Elevation (ft)
Bank Sta
1864
1860
1860
1858
1858
1856
1856
1854
1854
1852
1852 0
50
100
150
200
0
Station (ft)
50
100
150
200
Station (ft)
3
Clay Street Hydrology/Hydraulics
Clay Street
Plan: Existing Clay Street Legend WS 100 YR WS 50 YR
1870
Ground LOB ROB
Elevation (ft)
1860
0
200
400
600
800
1000
Deck
1175
1079
931 Clay St Bridge
500
1840
861
645 Bedford Ave Bridge
1850
1200
Main Channel Distance (ft)
Figure 6 –Existing conditions 50-yr and 100-yr profile.
Approximately 249' upstream from Clay Street Bridge is a deck off of a building that spans over the channel. The deck is approximately 22' x 50' and it contains one pier that is one foot wide. Approximately 282' downstream of Clay Street Bridge is Bedford Avenue Bridge. This bridge is 19' wide with a 26' span. The existing model was run with the flows described previously. Results in the vicinity of Clay Street Bridge are presented in the following tables. Table 3: 50-yr water surface elevations and velocities for the existing bridge. Cross-section (River Sta)
Location Relative to Bridge
WSEL (feet)
Channel Velocity (fps)
294' upstream
1870.0
7.2
1175
234' upstream
1866.4
13.9
1079
138' upstream
1865.5
10.6
953
12' upstream
1865.2
10.0
931
11' downstream
1862.7
16.2
861
81' downstream
1863.9
7.2
1235 Deck off of house
Clay Street Bridge
4
Clay Street Hydrology/Hydraulics
Cross-section (River Sta)
Location Relative to Bridge
WSEL (feet)
Channel Velocity (fps)
268' downstream
1863.6
6.4
645
297' downstream
1860.6
13.1
500
442' downstream
1859.9
10.6
0
942' downstream
1849.9
10.6
674 Bedford Ave Bridge
Table 4: 100-yr water surface elevations and velocities for the existing bridge. Cross-section (River Sta)
Location Relative to Bridge
WSEL (feet)
Channel Velocity (fps)
294' upstream
1870.6
6.8
1175
234' upstream
1867.3
13.9
1079
138' upstream
1867.7
8.2
953
12' upstream
1866.7
10.3
931
11' downstream
1863.5
17.0
861
81' downstream
1864.3
7.7
674
268' downstream
1864.0
6.8
645
297' downstream
1862.1
10.9
500
442' downstream
1860.3
10.8
0
942' downstream
1850.3
10.8
1235 Deck off of house
Clay Street Bridge
Bedford Ave Bridge
As seen in the profile and related tables the existing bridge will nearly overtop during the 100-yr flood event and will pass the 50-yr flow with no clearance to the soffit.
Proposed Conditions Model The existing conditions model was modified to create the proposed conditions model. The proposed conditions model contains the new bridge geometry provided by Quincy Engineering, Inc. The proposed geometry was inserted into the model based on the provided plans shown in Appendix A. The alternative with the 2'-0" thick cast-in-place reinforced concrete slab was modeled for this analysis as hydraulically the most conservative alternative. If the alternative with the thicker slab meets clearance requirements then the other alternative will also meet clearance requirements. The proposed single span bridge will exceed the total width of the existing bridge by approximately 26'-6". Since the proposed bridge is much wider than the existing bridge, additional cross sections upstream and downstream from the bridge were created based on the topography provided by Quincy Engineering. The right side of the bridge was brought in 2 feet to account for debris that could potentially gather around the right side of the bridge abutment. Figure 7 and 8 show HEC-RAS cross-sections upstream and downstream of Clay Street Bridge. Figure 9 shows a profile through the new bridge. The top of the new bridge deck (not including the concrete barrier and hand railing) is at an elevation of 1868.57 feet and the bottom soffit of the bridge is at an elevation of 1866.57 feet.
5
Clay Street Hydrology/Hydraulics
Clay Street Plan: Final_Proposed Clay Street RS = 967.25 BR Clay Street Bridge .045
Clay Street Plan: Final_Proposed Clay Street RS = 967.25 BR Clay Street Bridge
.03
.045
1870
.03
1870
Legend
Legend
WS 100 YR
WS 100 YR
1868
1868 WS 50 YR
WS 50 YR
Ground
1866
Ground
1866
Ineff
1862
1862
1860
1860
1858
1858
1856
1856
1854 -40
-20
0
20
40
60
Bank Sta
1864 Elevation (ft)
Elevation (ft)
Ineff
Bank Sta
1864
1854 -40
80
-20
0
20
Station (ft)
40
60
80
Station (ft)
Figure 7 – Proposed conditions cross section (upstream).
Clay Street
Figure 8 – Proposed conditions cross section (downstream).
Plan: Final_Proposed Clay Street
Hangtow n Creek Clay Street 1875
Legend WS 100 YR
1870
WS 50 YR Ground LOB
1865
ROB
Elevation (ft)
1860
1855
Deck
1175
1079
1034.75
Clay St Bridge
500
1840
861
645 Bedford Ave Bridge
1845
921.25
1850
1835 0
200
400
600
800
1000
1200
1400
Main Channel Distance (ft)
Figure 9 – Proposed conditions 50-yr and 100-yr profile.
The same flow rates as in the existing conditions model were run with the new bridge in place. Results in the vicinity of the new bridge are presented in the following tables. Table 5: 50-yr water surface elevations and velocities for the proposed bridge. Cross-section (River Sta) 1235
WSEL (feet)
Channel Velocity (fps)
245' upstream
1870.0
6.7
185' upstream
1866.4
13.8
Location Relative to Bridge
Deck off of house 1175
6
Clay Street Hydrology/Hydraulics
Cross-section (River Sta)
Location Relative to Bridge
WSEL (feet)
Channel Velocity (fps) 9.2
1079
89' upstream
1866.3
1034.75
45' upstream
1866.4
7.6
995.25
5' upstream
1864.9
11.1
939.25
5' downstream
1863.1
14.2
921.25
23’ downstream
1863.4
10.3
861
84' downstream
1863.9
7.2
674
271' downstream
1863.6
6.4
645
300' downstream
1860.6
13.1
500
445' downstream
1859.9
10.6
0
945' downstream
1849.9
10.6
Clay Street Bridge
Bedford Ave Bridge
Table 6: 100-yr water surface elevations and velocities for the proposed bridge. WSEL (feet)
Channel Velocity (fps)
245' upstream
1870.6
6.9
1175
185' upstream
1867.3
13.9
1079
89' upstream
1867.3
9.0
1034.75
45' upstream
1867.3
7.8
995.25
5' upstream
1865.6
11.8
939.25
5' downstream
1863.9
14.6
921.25
23’ downstream
1863.5
11.7
861
84' downstream
1864.3
7.7
674
271' downstream
1864.0
6.8
645
300' downstream
1862.1
10.9
500
445' downstream
1860.3
10.8
0
945' downstream
1850.3
10.8
Cross-section (River Sta) 1235
Location Relative to Bridge
Deck off of house
Clay Street Bridge
Bedford Ave Bridge
Based on the results, the proposed bridge deck will have 1.73 feet of clearance between the deck soffit and the 50-yr water surface and can pass the 100-yr flow with 1.0 foot of clearance (shown in Table 7), therefore, exceeding clearance and freeboard requirements. It is important to note that freeboard was calculated from top of deck and clearance was calculated from soffit. Table 7: Top of deck freeboard and soffit clearance for 50-yr and 100-yr events. 100-yr Freeboard (ft)
50-yr Freeboard (ft)
100-yr Soffit Clearance (ft)
50-yr Soffit Clearance (ft)
Existing Conditions
0.5
2.0
0.0
0.0
Proposed Condition
3.0
3.73
1.0
1.73
7
Clay Street Hydrology/Hydraulics
Table 8 provides a comparison between existing conditions and the proposed bridge conditions water surfaces immediately upstream of the bridges and at cross section 861 downstream of the bridges. The models show no difference in water surface elevations downstream from the bridge. The models show that the upstream water surface elevations decrease with the new bridge. The models also show the velocities slowing down through the new bridge. Therefore, the new bridge will have no negative impacts to the Hangtown Creek floodplain. Table 8: Comparison of water surface elevations and velocities for 50-yr and 100-yr events. 100-year Event
50-yr Event
WSE Downstream of Bridge (ft)
WSE Upstream of Bridge (ft)
Velocity through Bridge (fps)
WSE Downstream of Bridge (ft)
WSE Upstream of Bridge (ft)
Velocity through Bridge (fps)
Existing Conditions
1864.3
1866.8
16.6
1863.9
1865.3
15.2
Proposed Condition
1864.3
1865.6
11.9
1863.9
1864.9
11.3
Difference
0.0
-1.2
-4.7
0.0
-0.4
-3.9
C E D A R R AV I N E H Y D R A U L I C S Existing Conditions Model An existing conditions computer model was created for Cedar Ravine using the Army Corps of Engineers' Hydrologic Engineering Center River Analysis System (HEC-RAS version 3.1.3). Survey by Area West Engineers provided cross sections upstream on Cedar Ravine. The modeled portion of Cedar Ravine consists of approximately 40 feet of open channel that flows into a 4' x 7.8' box culvert. The box culvert extends for about 234 feet and then it transitions into a 66" corrugated metal pipe that extends for approximately 286 feet where it outlets into Hangtown Creek. Due to limited survey, all lengths and dimensions were approximated during a site visit. A Manning's n-value of 0.025 was used for the open channel segment of Cedar Ravine. Manning's nvalues of 0.017 and 0.024 were used for the box culvert segment and corrugated metal pipe segment, respectively. Cross sections and Manning's n-values downstream from the confluence of Hangtown Creek and Cedar Ravine remained the same as in the existing conditions model for Hangtown Creek.
Figure 10 –Manning's n-value of 0.025 for Cedar Ravine.
8
Figure 11 –Manning's n-value of 0.017 for box culvert.
Clay Street Hydrology/Hydraulics
The results show that Cedar Ravine cannot convey the 50-yr and 100-yr event flows through the culverts and some roadway flooding is anticipated during major storm events. Table 9 shows results for the culvert. Table 9: Flow vs. capacity for Cedar Ravine culvert. Location
Flow Rate (cfs)
Approximate flow conveyed in culvert
300
50-yr event flow
381
100-yr event flow
450
S C O U R A N A LY S I S A scour analysis of the Clay Street Bridge at Hangtown Creek was performed for the proposed bridge replacement (cast-in-place 2'-0" reinforced concrete slab). The other alternative was not analyzed because there should not be any significant difference in scour due to similar bridge alignment and dimensions. Evaluation of scour at the bridge is based on criteria and methodologies developed by the Federal Highways Administration, Hydraulic Circular No. 18 (HEC-18), Evaluating Scour at Bridges (February 1993). The analysis estimates scour potential that is based primarily on channel hydraulics, without consideration for streambed surface and subsurface conditions. It should be noted that the predictive scour equations were developed from laboratory tests using fine granular materials. The resulting values of estimated potential scour are typically conservative, especially in cases where the depth to scour resistant materials is shallower than the estimated scour depth.
H y d r a u l i c Va r i a b l e s Hydraulics variables such as channel flow, velocity and depth are adapted from the HEC-RAS Hydraulic Model for Hangtown Creek at the proposed Clay Street Bridge.
Soils Investigation A preliminary foundation report was created by Taber. The report states that the stream channel contains bedrock that shows little erosion from flow and it appears to be scour resistant. Although the extent and depth of bedrock in the channel was not stated, the depth of scour resistant materials can be expected to be less than the calculated scour depths. When designing bridge foundations, depth to this scour resistant material should be accurately determined.
L o n g Te r m A g g r a d a t i o n a n d D e g r a d a t i o n Long term changes in streambeds may be either by aggradation (filling) or degradation (cutting) of the streambed over long periods of time. Long term changes differ from short term modifications in that changes are not apparent within the year, as is the case with local scour of the streambed at bridges. Generally, short term (local) changes result from bridge hydraulics, while long-term changes are associated with changes in the hydraulics of the stream itself. Thus, long-term changes are noticeable throughout the stream reach and not just at bridge locations.
9
Clay Street Hydrology/Hydraulics
Due to the presence of exposed bedrock along the channel bottom of Hangtown Creek, there are no significant signs of long-term aggradation or degradation. However, a value of 1 foot degradation has been assumed for conservative analysis.
Contraction and Pier Scour There is no contraction scour due to the alignment of the new bridge and there is no pier scour because the new single span bridge does not have piers.
Local Abutment Scour Local abutment scour occurs when the abutment obstructs the flow. In the case of the Clay Street Bridge the right and left abutment scour is fairly similar. The abutment scour was calculated using Froehlich’s equation as described in HEC-18. The abutment scour was calculated for the worst case conditions using the channel capacity flow conditions. ⎛ a' Ys = 2.27 × K 1 × K 2 × ⎜⎜ Ya ⎝ Ya
⎞ ⎟⎟ ⎠
0.43
× Fr 0.61 + 1
where : K 1 = vertical wall K 2 = angle coeff. a' = Projection into Normal flow Ya = average depth of flow on the floodplain Fr = Froude number of approach upstream of the abutment Fr =
Ve (g × y a )1/2
Ve = Average velocity in overbank g = 32.2 ft/sec
Table 10 below shows the variables for the right and left abutment scour calculations and the total scour calculated. Table 10. Variables for abutment scour calculations. Right Abutment
Left Abutment
K1
1.0
1.0
K2
1.0
1.0
a’ (ft)
15.9
56.4
Fr
0.37
0.41
ya (ft)
1.85
0.85
ys (ft)
7.6
7.7
10
Clay Street Hydrology/Hydraulics
To t a l S c o u r P o t e n t i a l a n d R e c o m m e n d a t i o n s The scour potential at the Clay Street Bridge at Hangtown Creek consists mostly of abutment scour. The maximum scour expected at the abutments is 7.6 feet for the right abutment and 7.7 feet for the left abutment. However, it is important to note that bedrock exists in this area and that abutment scour will only occur to the depth of bedrock. Rock protection is recommended at the abutments if foundation exposure is an issue. If rock protection is necessary, it should consist of standard Caltrans facing material with a minimum thickness of 1.8 feet for a width of 5 feet along each abutment. Significant scour is not anticipated at the confluence of Hangtown Creek and Cedar Ravine due to the proposed alignment of the new bridge and the outlet of Cedar Ravine. The proposed alignment of Cedar Ravine outlet will direct flow inline (parallel) with the flow of Hangtown Creek reducing cross bank flow and turbulence from that of the existing alignment. The existing rock channel bottom has not experienced significant sour downstream of the confluence, therefore the improved condition is not expected to show any measurable scour. If existing rock downstream from the culvert outlet is removed during construction it should be replaced in-kind or using Caltrans facing material as described above. The limits of the rock protection should extend approximately 20 feet downstream from the culvert outlet.
11
Clay Street Hydrology/Hydraulics
APPENDIX A - PROPOSED BRIDGE PLANS
Clay Street Bridge H & H Analysis
APPENDIX B - HEC-HMS OUTPUT
Clay Street Bridge H & H Analysis
HEC-HMS SCHEMATIC FOR THE 50-YR AND 100-YR EVENTS
AREA OF INTEREST
Project: Clay Street Brdg
Simulation Run: Existing 50YR
Start of Run: 01Jan2006, 00:00 End of Run: 02Jan2006, 00:00 Compute Time: 15Nov2007, 08:45:30 Volume Units:
Basin Model: Existing Meteorologic Model: GAGE 50YR Control Specifications: 1-day
AC-FT
Hydrologic Element
Drainage Area (MI2)
Peak Discharge Time of Peak (CFS)
Volume (AC-FT)
A1
0.5950
363.55
01Jan2006, 12:32
116.64
C1
0.4761
267.69
01Jan2006, 12:32
92.32
C2
0.0555
44.48
01Jan2006, 12:16
12.53
C3
0.3050
238.37
01Jan2006, 12:17
61.51
CR
0.8366
381.27
01Jan2006, 12:20
165.60
HC_CR
5.5396
2782.33
01Jan2006, 12:33
1023.52
HT1
0.2400
138.65
01Jan2006, 12:30
43.21
HT2
0.3160
208.84
01Jan2006, 12:21
57.82
HT3
0.1680
154.25
01Jan2006, 12:19
41.95
HT4
0.1010
104.94
01Jan2006, 12:18
29.34
HT5
0.0650
47.77
01Jan2006, 12:17
12.32
HT6
0.0750
63.96
01Jan2006, 12:16
16.59
HT7
0.0720
63.94
01Jan2006, 12:22
18.36
J1
1.3180
597.39
01Jan2006, 12:41
205.10
J2
4.6310
2396.34
01Jan2006, 12:32
841.32
J3
0.7660
522.51
01Jan2006, 12:24
155.57
J4
1.6010
1021.15
01Jan2006, 12:29
314.74
J5
1.9170
1205.27
01Jan2006, 12:28
372.31
J6
2.4650
1456.65
01Jan2006, 12:29
472.60
J7
2.8080
1595.69
01Jan2006, 12:30
527.30
J9
0.3100
108.74
01Jan2006, 12:31
45.37
L1
0.0500
21.69
01Jan2006, 12:25
6.36
L1.2
0.0960
50.38
01Jan2006, 12:15
12.75
L1.3
0.1360
65.88
01Jan2006, 12:28
20.01
L2
0.0700
60.10
01Jan2006, 12:10
13.73
Page 1
Hydrologic Element
Drainage Area (MI2)
Peak Discharge Time of Peak (CFS)
Volume (AC-FT)
L2.2
0.0280
34.11
01Jan2006, 12:04
6.67
R1
0.5340
239.58
01Jan2006, 12:38
81.67
R1-R2
0.5340
239.48
01Jan2006, 12:46
80.93
R2
0.7840
370.43
01Jan2006, 12:36
124.17
R2-R3
1.3180
597.16
01Jan2006, 12:46
203.84
R3
0.4300
331.91
01Jan2006, 12:22
94.13
RC1
0.5316
236.37
01Jan2006, 12:56
104.09
RES-C1
0.5316
236.44
01Jan2006, 12:48
104.81
RES-LL
0.1860
76.92
01Jan2006, 12:37
25.98
RHT-1
0.7660
522.20
01Jan2006, 12:28
154.89
RHT-10
0.1860
76.92
01Jan2006, 12:38
25.95
RHT-11
0.3100
108.73
01Jan2006, 12:32
45.35
RHT-12
0.3100
108.72
01Jan2006, 12:33
45.28
RHT-2
1.6010
1020.83
01Jan2006, 12:30
314.49
RHT-6
1.9170
1204.82
01Jan2006, 12:30
371.63
RHT-7
2.4650
1452.78
01Jan2006, 12:31
471.28
RHT-8
2.8080
1594.41
01Jan2006, 12:31
526.76
RHT-9
4.6310
2389.18
01Jan2006, 12:34
839.56
S1
0.1770
53.84
01Jan2006, 12:15
14.35
SM1
0.5850
380.84
01Jan2006, 12:26
113.84
SM2
0.1810
154.46
01Jan2006, 12:19
41.74
Page 2
Project: Clay Street Brdg
Simulation Run: Gage 100YR
Start of Run: 01Jan2006, 00:00 End of Run: 02Jan2006, 00:00 Compute Time: 15Nov2007, 08:43:49 Volume Units:
Basin Model: Existing Meteorologic Model: Gage 100YR Control Specifications: 1-day
AC-FT
Hydrologic Element
Drainage Area (MI2)
Peak Discharge Time of Peak (CFS)
Volume (AC-FT)
A1
0.5950
418.01
01Jan2006, 12:31
133.73
C1
0.4761
308.36
01Jan2006, 12:32
105.87
C2
0.0555
50.90
01Jan2006, 12:16
14.27
C3
0.3050
276.06
01Jan2006, 12:16
71.79
CR
0.8366
450.13
01Jan2006, 12:42
191.07
HC_CR
5.5396
3219.30
01Jan2006, 12:33
1183.79
HT1
0.2400
160.91
01Jan2006, 12:29
49.95
HT2
0.3160
243.03
01Jan2006, 12:21
66.97
HT3
0.1680
174.17
01Jan2006, 12:18
47.52
HT4
0.1010
116.79
01Jan2006, 12:18
32.72
HT5
0.0650
55.56
01Jan2006, 12:17
14.39
HT6
0.0750
73.34
01Jan2006, 12:16
19.09
HT7
0.0720
71.83
01Jan2006, 12:22
20.90
J1
1.3180
703.50
01Jan2006, 12:40
240.59
J2
4.6310
2789.80
01Jan2006, 12:32
973.90
J3
0.7660
602.14
01Jan2006, 12:24
179.02
J4
1.6010
1176.67
01Jan2006, 12:29
361.91
J5
1.9170
1391.98
01Jan2006, 12:28
428.59
J6
2.4650
1686.46
01Jan2006, 12:28
545.03
J7
2.8080
1849.82
01Jan2006, 12:30
609.04
J9
0.3100
130.86
01Jan2006, 12:30
53.81
L1
0.0500
26.22
01Jan2006, 12:25
7.61
L1.2
0.0960
61.18
01Jan2006, 12:15
15.32
L1.3
0.1360
78.19
01Jan2006, 12:28
23.57
L2
0.0700
70.39
01Jan2006, 12:10
15.99
Page 1
Hydrologic Element
Drainage Area (MI2)
Peak Discharge Time of Peak (CFS)
Volume (AC-FT)
L2.2
0.0280
40.03
01Jan2006, 12:04
7.80
R1
0.5340
282.26
01Jan2006, 12:37
95.59
R1-R2
0.5340
282.14
01Jan2006, 12:46
94.74
R2
0.7840
434.69
01Jan2006, 12:36
145.85
R2-R3
1.3180
703.16
01Jan2006, 12:46
239.11
R3
0.4300
379.04
01Jan2006, 12:22
107.29
RC1
0.5316
330.37
01Jan2006, 12:43
119.28
RES-C1
0.5316
335.41
01Jan2006, 12:35
120.09
RES-LL
0.1860
92.06
01Jan2006, 12:37
30.71
RHT-1
0.7660
601.78
01Jan2006, 12:28
178.24
RHT-10
0.1860
92.04
01Jan2006, 12:38
30.68
RHT-11
0.3100
130.82
01Jan2006, 12:30
53.79
RHT-12
0.3100
130.81
01Jan2006, 12:32
53.71
RHT-2
1.6010
1176.32
01Jan2006, 12:30
361.62
RHT-6
1.9170
1391.44
01Jan2006, 12:30
427.81
RHT-7
2.4650
1682.13
01Jan2006, 12:31
543.49
RHT-8
2.8080
1848.20
01Jan2006, 12:31
608.41
RHT-9
4.6310
2780.51
01Jan2006, 12:34
971.82
S1
0.1770
70.99
01Jan2006, 12:15
18.43
SM1
0.5850
440.21
01Jan2006, 12:26
131.44
SM2
0.1810
176.62
01Jan2006, 12:19
47.57
Page 2
APPENDIX C - HEC-RAS OUTPUT FOR HANGTOWN CREEK
Clay Street Bridge H & H Analysis
HEC-RAS Plan: Existing River: Hangtown Creek Reach: Clay Street Reach
River Sta
Profile
Q Total
Min Ch El
W.S. Elev
Crit W.S.
E.G. Elev
E.G. Slope
Vel Chnl
Flow Area
Top Width
(cfs)
(ft)
(ft)
(ft)
(ft)
(ft/ft)
(ft/s)
(sq ft)
(ft)
Froude # Chl
Clay Street
1235
100 YR
2852.00
1857.75
1870.61
1867.31
1871.22
0.002226
6.79
474.51
88.24
0.38
Clay Street
1235
50 YR
2453.00
1857.75
1870.02
1866.39
1870.61
0.002279
6.64
422.51
88.24
0.38
Clay Street
1190
Clay Street
1175
100 YR
2852.00
1857.75
1867.31
1867.31
1870.28
0.014654
13.89
208.62
38.96
0.94
Clay Street
1175
50 YR
2453.00
1857.75
1866.39
1866.39
1869.38
0.017418
13.89
176.61
30.69
1.01
Clay Street
1079
100 YR
2852.00
1856.40
1867.71
1868.75
0.005667
8.24
361.13
99.30
0.57
Clay Street
1079
50 YR
2453.00
1856.40
1865.53
1867.27
0.013011
10.57
232.09
45.18
0.82
Clay Street
953
100 YR
2852.00
1852.69
1866.70
1861.84
1868.36
0.001495
10.33
276.19
183.84
0.50
Clay Street
953
50 YR
2453.00
1852.69
1865.20
1861.03
1866.76
0.001656
10.03
244.66
32.05
0.52
Clay Street
941.5
Clay Street
931
100 YR
3219.00
1853.20
1863.49
1863.49
1867.99
0.004535
17.03
189.05
46.71
1.00
Clay Street
931
50 YR
2782.00
1853.20
1862.65
1862.65
1866.74
0.004686
16.22
171.52
44.32
1.00
Clay Street
861
100 YR
3219.00
1852.08
1864.26
1865.07
0.002850
7.66
479.25
112.40
0.46
Clay Street
861
50 YR
2782.00
1852.08
1863.89
1864.61
0.002649
7.17
438.25
107.15
0.44
Clay Street
674
100 YR
3219.00
1850.42
1863.98
1862.14
1864.56
0.002002
6.81
558.35
108.91
0.36
Clay Street
674
50 YR
2782.00
1850.42
1863.63
1859.44
1864.14
0.001829
6.38
520.12
108.91
0.34
Clay Street
659.5
Clay Street
645
100 YR
3219.00
1850.42
1862.14
1862.14
1863.74
0.005943
10.85
357.76
108.91
0.62
Clay Street
645
50 YR
2782.00
1850.42
1860.64
1859.44
1863.30
0.010464
13.10
214.22
81.01
0.81
Clay Street
500
100 YR
3219.00
1847.91
1860.32
1860.32
1861.87
0.007719
10.75
358.30
108.90
0.65
Clay Street
500
50 YR
2782.00
1847.91
1859.86
1859.86
1861.42
0.008063
10.59
308.77
103.30
0.66
Clay Street
0
100 YR
3219.00
1837.91
1850.32
1850.32
1851.87
0.007719
10.75
358.30
108.90
0.65
Clay Street
0
50 YR
2782.00
1837.91
1849.86
1849.86
1851.42
0.008063
10.59
308.77
103.30
0.66
Bridge
Bridge
Bridge
1
HEC-RAS Plan: Final_Proposed River: Hangtown Creek Reach: Clay Street Reach
River Sta
Profile
Q Total (cfs) 2852.00
Min Ch El (ft) 1857.75
W.S. Elev (ft) 1870.60
Crit W.S. (ft) 1867.29
E.G. Elev (ft) 1871.22
E.G. Slope (ft/ft) 0.002148
Vel Chnl (ft/s) 6.86
Flow Area (sq ft) 473.51
Top Width (ft) 88.24
Froude # Chl
2453.00
1857.75
1870.01
1866.39
1870.60
0.002192
6.70
421.50
88.24
0.38
1867.29 1866.41
1870.29 1869.38
0.013875 0.016189
13.92 13.84
208.12 177.23
38.85 30.87
0.94 1.00
Clay Street
1235
100 YR
Clay Street
1235
50 YR
0.38
Clay Street
1190
Clay Street Clay Street
1175 1175
100 YR 50 YR
2852.00 2453.00
1857.75 1857.75
1867.29 1866.41
Clay Street
1079
100 YR
2852.00
1856.40
1867.28
1868.53
0.007300
8.97
320.71
79.31
0.64
Clay Street
1079
50 YR
2453.00
1856.40
1866.29
1867.59
0.008831
9.18
267.32
48.57
0.69
Clay Street Clay Street
1034.75 1034.75
100 YR 50 YR
2852.00 2453.00
1856.00 1856.00
1867.31 1866.36
1863.82 1863.24
1868.25 1867.25
0.002764 0.003062
7.78 7.55
366.62 324.79
112.58 90.13
0.48 0.49
Clay Street
995.25
100 YR
2852.00
1855.00
1865.61
1864.04
1867.76
0.003911
11.75
242.69
87.77
0.73
Clay Street
995.25
50 YR
2453.00
1855.00
1864.89
1863.33
1866.80
0.003954
11.10
220.98
57.06
0.72
Clay Street
967.25
Clay Street Clay Street
939.25 939.25
100 YR 50 YR
2852.00 2453.00
1854.50 1854.50
1863.85 1863.10
1863.85 1863.10
1867.17 1866.21
0.008068 0.008266
14.63 14.15
194.90 173.37
50.22 47.75
1.00 1.01
Clay Street Clay Street
921.25 921.25
100 YR 50 YR
3219.00 2782.00
1854.00 1854.00
1863.53 1863.41
1865.67 1865.06
0.003878 0.003046
11.73 10.29
274.49 270.36
46.64 46.27
0.74 0.65
Clay Street Clay Street
861 861
100 YR 50 YR
3219.00 2782.00
1852.08 1852.08
1864.26 1863.89
1865.07 1864.61
0.002850 0.002649
7.66 7.17
479.25 438.25
112.40 107.15
0.46 0.44
Clay Street Clay Street
674 674
100 YR 50 YR
3219.00 2782.00
1850.42 1850.42
1863.98 1863.63
1862.14 1859.44
1864.56 1864.14
0.002002 0.001829
6.81 6.38
558.35 520.12
108.91 108.91
0.36 0.34
Clay Street
659.5
Clay Street Clay Street
645 645
100 YR 50 YR
3219.00 2782.00
1850.42 1850.42
1862.14 1860.64
1862.14 1859.44
1863.74 1863.30
0.005943 0.010464
10.85 13.10
357.76 214.22
108.91 81.01
0.62 0.81
Clay Street Clay Street
500 500
100 YR 50 YR
3219.00 2782.00
1847.91 1847.91
1860.32 1859.86
1860.32 1859.86
1861.87 1861.42
0.007719 0.008063
10.75 10.59
358.30 308.77
108.90 103.30
0.65 0.66
Clay Street Clay Street
0 0
100 YR 50 YR
3219.00 2782.00
1837.91 1837.91
1850.32 1849.86
1850.32 1849.86
1851.87 1851.42
0.007719 0.008063
10.75 10.59
358.30 308.77
108.90 103.30
0.65 0.66
Bridge
Bridge
Bridge
1
A P P E N D I X D - H E C - R A S O U T P U T F O R C E D A R R AV I N E
Clay Street Bridge H & H Analysis
HEC-RAS Plan: Existing River: Cedar Ravine Reach: Cedar Ravine Reach
River Sta
Profile
Q Total
Min Ch El
W.S. Elev
Crit W.S.
E.G. Elev
E.G. Slope
Vel Chnl
Flow Area
Top Width
Froude # Chl
(cfs) 450.00
(ft) 1870.16
(ft) 1878.05
(ft) 1875.34
(ft) 1878.28
(ft/ft) 0.001029
(ft/s) 4.40
(sq ft) 129.87
(ft) 50.18
0.29
381.00
1870.16
1876.38
1874.78
1877.16
0.004098
7.32
59.29
28.43
0.56
1876.94 1876.48
0.001673 0.002130
5.36 5.71
106.74 80.94
50.18 40.46
0.37 0.41
Cedar Ravine
1536
100YR
Cedar Ravine
1536
50YR
Cedar Ravine
1521
Cedar Ravine Cedar Ravine
1506 1506
100YR 50YR
450.00 381.00
1869.16 1869.16
1876.59 1876.04
Cedar Ravine
1466
100YR
450.00
1868.66
1876.65
1873.40
1876.85
0.000939
4.07
137.11
50.18
0.27
Cedar Ravine
1466
50YR
381.00
1868.66
1876.13
1872.86
1876.36
0.001157
4.30
110.82
50.18
0.29
Cedar Ravine
1345.25
Cedar Ravine Cedar Ravine
1224.5 1224.5
1864.17 1864.17
1874.11 1873.10
1870.09 1869.46
1874.94 1873.88
0.002390 0.002453
7.29 7.08
61.74 53.78
7.83 7.83
0.46 0.48
Cedar Ravine
1077.75
Cedar Ravine Cedar Ravine
931 931
100YR 50YR
450.00 381.00
1853.20 1853.20
1863.42 1863.27
1865.14 1864.55
0.002918 0.002237
10.51 9.08
42.84 41.98
46.53 46.08
0.66 0.58
Cedar Ravine Cedar Ravine
861 861
100YR 50YR
450.00 381.00
1852.08 1852.08
1864.26 1863.89
1864.28 1863.90
0.000056 0.000050
1.07 0.98
479.39 438.76
112.41 107.22
0.06 0.06
Bridge
Culvert 100YR 50YR
450.00 381.00 Culvert
1855.31 1855.05
1
